This patch will:

- Add two new handlerton functions to get and set the server version number
  stored in the dictionary tablespace header.
- Implement the two functions for InnnoDB. Setting the server version is
  implemented by modifying the existing function 'upgrade_space_version()'.
- Add a new function to the bootstrap context singleton to keep track of
  server versions from which upgrade is supported. Currently, this set
  contains all post-GA 8.0 versions.
- Add a check during server bootstrap where we get hold of the server version
  number from the dictionary tablespace, and verify that this is a version
  from which we are allowed to upgrade.
- Move the update of the actual server version number in the bootstrap context
  from the end of do_upgrade_checks() to update_versions(), and also update the
  server version number in the dictionary tablespace header at the same time.
- Introduce new MTR include predicate not_freebsd.inc and add that one and
  freebsd.inc to excludenoskip.list.

Semi-related to the issues above, this patch will also:

- Add a new MTR test to list the contents of the DD table 'mysql.dd_properties'
  in a human readable format. This will catch accidential changes to the
  contents of this table.
- Add a zipped datadir from 8.0.13 and extend the relevant dd_schema_definition
  test to verify correct upgrade from 8.0.13.
- Refactor the existing test dd_schema_definition_after_upgrade_debug and
  separate out common code as an include file. The test will also verify that
  the contents of the mysql.dd_properties table is the same for an upgraded
  server as it is for a newly initialized server (with the exception of ids,
  root page numbers, etc.).
- Swap the order of the steps in migrate_meta_data() adressing the mysql.tables
  DD table. We need to first complete the in place updates before inserting the
  meta data into the new table version.

Unrelated to the above, this patch will also:

- Update and enable a test cases in main.partition, but keep the original
  test case commented out until support for partitions in shared tablespaces
  is re-implemented.
- Remove sql/dd/mtr_readme.txt since this file is now obsolete.
- Change have_mac_os.inc to check also for MacOS, not just the obsoleted OSX.
- Fix the test resource_group_unsupported, which was using illegal syntax.

Change-Id: Idac1ea7bf3a264e7035e048179f7de89c435f272